Adds strict type checking and clear split between cfg and implementation (#4718)

# Description

Adds strict type checking and split between cfg and implementaion

Fixes # (issue)

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## Type of change

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- Bug fix (non-breaking change which fixes an issue)

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## Checklist

- [x] I have read and understood the [contribution
guidelines](https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html)
- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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Author: ooctipus

docs/source/features/hydra.rst

@@ -108,7 +108,7 @@ are modified.
 
 For example, for the configuration of the Cartpole camera depth environment:
 
-.. literalinclude:: ../../../source/isaaclab_tasks/isaaclab_tasks/direct/cartpole/cartpole_camera_env.py
+.. literalinclude:: ../../../source/isaaclab_tasks/isaaclab_tasks/direct/cartpole/cartpole_camera_env_cfg.py
     :language: python
     :start-at: class CartpoleDepthCameraEnvCfg
     :end-at: tiled_camera.width

source/isaaclab/isaaclab/controllers/config/rmp_flow.py

@@ -5,41 +5,34 @@
 
 import os
 
-from isaacsim.core.utils.extensions import get_extension_path_from_name
-
-from isaaclab.controllers.rmp_flow import RmpFlowControllerCfg
+from isaaclab.controllers.rmp_flow_cfg import RmpFlowControllerCfg
 from isaaclab.utils.assets import ISAACLAB_NUCLEUS_DIR
 
 # Directory on Nucleus Server for RMP-Flow assets (URDFs, collision models, etc.)
 ISAACLAB_NUCLEUS_RMPFLOW_DIR = os.path.join(ISAACLAB_NUCLEUS_DIR, "Controllers", "RmpFlowAssets")
 
-# Note: RMP-Flow config files for supported robots are stored in the motion_generation extension
-# We need to move it here for doc building purposes.
-try:
-    _RMP_CONFIG_DIR = os.path.join(
-        get_extension_path_from_name("isaacsim.robot_motion.motion_generation"),
-        "motion_policy_configs",
-    )
-except Exception:
-    _RMP_CONFIG_DIR = ""
+# Sentinel prefix for paths inside the isaacsim.robot_motion.motion_generation extension.
+# RmpFlowController resolves these at init time (after enabling the extension) so that
+# this cfg file stays free of any isaacsim/Kit imports.
+_EXT_MOTION_CFG = "rmpflow_ext:motion_policy_configs/"
 
 # Path to current directory
 _CUR_DIR = os.path.dirname(os.path.realpath(__file__))
 
 FRANKA_RMPFLOW_CFG = RmpFlowControllerCfg(
-    config_file=os.path.join(_RMP_CONFIG_DIR, "franka", "rmpflow", "franka_rmpflow_common.yaml"),
+    config_file=_EXT_MOTION_CFG + "franka/rmpflow/franka_rmpflow_common.yaml",
     urdf_file=os.path.join(_CUR_DIR, "data", "lula_franka_gen.urdf"),
-    collision_file=os.path.join(_RMP_CONFIG_DIR, "franka", "rmpflow", "robot_descriptor.yaml"),
+    collision_file=_EXT_MOTION_CFG + "franka/rmpflow/robot_descriptor.yaml",
     frame_name="panda_end_effector",
     evaluations_per_frame=5,
 )
 """Configuration of RMPFlow for Franka arm (default from `isaacsim.robot_motion.motion_generation`)."""
 
 
 UR10_RMPFLOW_CFG = RmpFlowControllerCfg(
-    config_file=os.path.join(_RMP_CONFIG_DIR, "ur10", "rmpflow", "ur10_rmpflow_config.yaml"),
-    urdf_file=os.path.join(_RMP_CONFIG_DIR, "ur10", "ur10_robot.urdf"),
-    collision_file=os.path.join(_RMP_CONFIG_DIR, "ur10", "rmpflow", "ur10_robot_description.yaml"),
+    config_file=_EXT_MOTION_CFG + "ur10/rmpflow/ur10_rmpflow_config.yaml",
+    urdf_file=_EXT_MOTION_CFG + "ur10/ur10_robot.urdf",
+    collision_file=_EXT_MOTION_CFG + "ur10/rmpflow/ur10_robot_description.yaml",
     frame_name="ee_link",
     evaluations_per_frame=5,
 )

source/isaaclab/isaaclab/controllers/rmp_flow.py

@@ -3,14 +3,14 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
-from dataclasses import MISSING
+import os
 
 import torch
 
 from isaacsim.core.prims import SingleArticulation
 
 # enable motion generation extensions
-from isaacsim.core.utils.extensions import enable_extension
+from isaacsim.core.utils.extensions import enable_extension, get_extension_path_from_name
 
 enable_extension("isaacsim.robot_motion.lula")
 enable_extension("isaacsim.robot_motion.motion_generation")
@@ -19,28 +19,27 @@
 from isaacsim.robot_motion.motion_generation.lula.motion_policies import RmpFlow, RmpFlowSmoothed
 
 import isaaclab.sim as sim_utils
-from isaaclab.utils import configclass
 from isaaclab.utils.assets import retrieve_file_path
 
+from .rmp_flow_cfg import RmpFlowControllerCfg  # noqa: F401
 
-@configclass
-class RmpFlowControllerCfg:
-    """Configuration for RMP-Flow controller (provided through LULA library)."""
+_RMPFLOW_EXT_PREFIX = "rmpflow_ext:"
+_RMPFLOW_EXT_NAME = "isaacsim.robot_motion.motion_generation"
 
-    name: str = "rmp_flow"
-    """Name of the controller. Supported: "rmp_flow", "rmp_flow_smoothed". Defaults to "rmp_flow"."""
-    config_file: str = MISSING
-    """Path to the configuration file for the controller."""
-    urdf_file: str = MISSING
-    """Path to the URDF model of the robot."""
-    collision_file: str = MISSING
-    """Path to collision model description of the robot."""
-    frame_name: str = MISSING
-    """Name of the robot frame for task space (must be present in the URDF)."""
-    evaluations_per_frame: float = MISSING
-    """Number of substeps during Euler integration inside LULA world model."""
-    ignore_robot_state_updates: bool = False
-    """If true, then state of the world model inside controller is rolled out. Defaults to False."""
+
+def _resolve_rmpflow_path(path: str) -> str:
+    """Resolve a sentinel ``rmpflow_ext:`` path to an absolute filesystem path.
+
+    Paths stored in :class:`~isaaclab.controllers.rmp_flow_cfg.RmpFlowControllerCfg`
+    that begin with ``"rmpflow_ext:"`` are relative to the
+    ``isaacsim.robot_motion.motion_generation`` extension directory.  This avoids
+    importing ``isaacsim`` in the cfg file (which is loaded without Kit).
+    """
+    if path.startswith(_RMPFLOW_EXT_PREFIX):
+        rel = path[len(_RMPFLOW_EXT_PREFIX) :]
+        ext_dir = get_extension_path_from_name(_RMPFLOW_EXT_NAME)
+        return os.path.join(ext_dir, rel)
+    return path
 
 
 class RmpFlowController:
@@ -98,9 +97,11 @@ def initialize(self, prim_paths_expr: str):
             robot.initialize()
             # download files if they are not local
 
-            local_urdf_file = retrieve_file_path(self.cfg.urdf_file, force_download=True)
-            local_collision_file = retrieve_file_path(self.cfg.collision_file, force_download=True)
-            local_config_file = retrieve_file_path(self.cfg.config_file, force_download=True)
+            local_urdf_file = retrieve_file_path(_resolve_rmpflow_path(self.cfg.urdf_file), force_download=True)
+            local_collision_file = retrieve_file_path(
+                _resolve_rmpflow_path(self.cfg.collision_file), force_download=True
+            )
+            local_config_file = retrieve_file_path(_resolve_rmpflow_path(self.cfg.config_file), force_download=True)
 
             # add controller
             rmpflow = controller_cls(

source/isaaclab/isaaclab/controllers/rmp_flow_cfg.py

@@ -0,0 +1,32 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Configuration for RMP-Flow controller."""
+
+from __future__ import annotations
+
+from dataclasses import MISSING
+
+from isaaclab.utils import configclass
+
+
+@configclass
+class RmpFlowControllerCfg:
+    """Configuration for RMP-Flow controller (provided through LULA library)."""
+
+    name: str = "rmp_flow"
+    """Name of the controller. Supported: "rmp_flow", "rmp_flow_smoothed". Defaults to "rmp_flow"."""
+    config_file: str = MISSING
+    """Path to the configuration file for the controller."""
+    urdf_file: str = MISSING
+    """Path to the URDF model of the robot."""
+    collision_file: str = MISSING
+    """Path to collision model description of the robot."""
+    frame_name: str = MISSING
+    """Name of the robot frame for task space (must be present in the URDF)."""
+    evaluations_per_frame: float = MISSING
+    """Number of substeps during Euler integration inside LULA world model."""
+    ignore_robot_state_updates: bool = False
+    """If true, then state of the world model inside controller is rolled out. Defaults to False."""

source/isaaclab/isaaclab/devices/gamepad/__init__.py

@@ -5,5 +5,7 @@
 
 """Gamepad device for SE(2) and SE(3) control."""
 
-from .se2_gamepad import Se2Gamepad, Se2GamepadCfg
-from .se3_gamepad import Se3Gamepad, Se3GamepadCfg
+from .se2_gamepad import Se2Gamepad
+from .se2_gamepad_cfg import Se2GamepadCfg
+from .se3_gamepad import Se3Gamepad
+from .se3_gamepad_cfg import Se3GamepadCfg

source/isaaclab/isaaclab/devices/gamepad/se2_gamepad.py

@@ -9,7 +9,7 @@
 
 import weakref
 from collections.abc import Callable
-from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 import numpy as np
 import torch
@@ -20,7 +20,10 @@
 
 from isaaclab.app.settings_manager import get_settings_manager
 
-from ..device_base import DeviceBase, DeviceCfg
+from ..device_base import DeviceBase
+
+if TYPE_CHECKING:
+    from .se2_gamepad_cfg import Se2GamepadCfg
 
 
 class Se2Gamepad(DeviceBase):
@@ -203,14 +206,3 @@ def _resolve_command_buffer(self, raw_command: np.ndarray) -> np.ndarray:
         command[command_sign] *= -1
 
         return command
-
-
-@dataclass
-class Se2GamepadCfg(DeviceCfg):
-    """Configuration for SE2 gamepad devices."""
-
-    v_x_sensitivity: float = 1.0
-    v_y_sensitivity: float = 1.0
-    omega_z_sensitivity: float = 1.0
-    dead_zone: float = 0.01
-    class_type: type[DeviceBase] = Se2Gamepad

source/isaaclab/isaaclab/devices/gamepad/se2_gamepad_cfg.py

@@ -0,0 +1,24 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Configuration for SE(2) gamepad controller."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from ..device_base import DeviceCfg
+from .se2_gamepad import Se2Gamepad
+
+
+@dataclass
+class Se2GamepadCfg(DeviceCfg):
+    """Configuration for SE2 gamepad devices."""
+
+    v_x_sensitivity: float = 1.0
+    v_y_sensitivity: float = 1.0
+    omega_z_sensitivity: float = 1.0
+    dead_zone: float = 0.01
+    class_type: type | str = Se2Gamepad

source/isaaclab/isaaclab/devices/gamepad/se3_gamepad.py

@@ -9,7 +9,7 @@
 
 import weakref
 from collections.abc import Callable
-from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 import numpy as np
 import torch
@@ -20,7 +20,10 @@
 
 from isaaclab.app.settings_manager import get_settings_manager
 
-from ..device_base import DeviceBase, DeviceCfg
+from ..device_base import DeviceBase
+
+if TYPE_CHECKING:
+    from .se3_gamepad_cfg import Se3GamepadCfg
 
 
 class Se3Gamepad(DeviceBase):
@@ -257,14 +260,3 @@ def _resolve_command_buffer(self, raw_command: np.ndarray) -> np.ndarray:
         delta_command[delta_command_sign] *= -1
 
         return delta_command
-
-
-@dataclass
-class Se3GamepadCfg(DeviceCfg):
-    """Configuration for SE3 gamepad devices."""
-
-    gripper_term: bool = True
-    dead_zone: float = 0.01  # For gamepad devices
-    pos_sensitivity: float = 1.0
-    rot_sensitivity: float = 1.6
-    class_type: type[DeviceBase] = Se3Gamepad

source/isaaclab/isaaclab/devices/gamepad/se3_gamepad_cfg.py

@@ -0,0 +1,24 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Configuration for SE(3) gamepad controller."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from ..device_base import DeviceCfg
+from .se3_gamepad import Se3Gamepad
+
+
+@dataclass
+class Se3GamepadCfg(DeviceCfg):
+    """Configuration for SE3 gamepad devices."""
+
+    gripper_term: bool = True
+    dead_zone: float = 0.01
+    pos_sensitivity: float = 1.0
+    rot_sensitivity: float = 1.6
+    class_type: type | str = Se3Gamepad

source/isaaclab/isaaclab/devices/keyboard/__init__.py

@@ -5,5 +5,7 @@
 
 """Keyboard device for SE(2) and SE(3) control."""
 
-from .se2_keyboard import Se2Keyboard, Se2KeyboardCfg
-from .se3_keyboard import Se3Keyboard, Se3KeyboardCfg
+from .se2_keyboard import Se2Keyboard
+from .se2_keyboard_cfg import Se2KeyboardCfg
+from .se3_keyboard import Se3Keyboard
+from .se3_keyboard_cfg import Se3KeyboardCfg